1. Field of the Invention
This invention relates to a filling compound for electrical and optical equipment in the form of cables, connectors, plugs etc. and to assemblies thus produced.
2. Discussion of Related Art
Electrical and optical equipment in the form of cables, connectors, plugs etc. has to be protected against harmful influences penetrating from outside, particularly water, and also against mechanical damage during laying or as a result of exposure to heat. This is because moisture penetrating at a given point spreads and thus adversely affects the performance of the line. This problem has been known for some time and various measures have already been proposed with a view to solving it. Thus, EP 0 206 234-B1 describes a filling compound consisting of 65 to 90% by weight mineral oil, 2 to 25% by weight of an organic thickener, more particularly a poly-.alpha.-olefin, 2 to 10% by weight of a highly disperse silica and, optionally, 0.2 to 10% by weight hollow microbeads and 0.1 to 5% by weight of a dispersant. Substantially the same composition is described in FR-PS 2 644 004.
Although compositions of the type in question are capable of satisfying the stringent requirements of the cable industry both in regard to performance properties and in regard to processability, even more exacting requirements, particularly in regard to extreme temperature influences, are now being imposed for certain applications. Thus, on the one hand, the filling compound should still be flexible at very low temperatures but, on the other hand, should not run out, even at extremely high temperatures. In addition, the filling compound should have a high flash point. The other requirements which filling compounds for electrical and optical equipment in the form of cables, connectors, plugs, etc. are normally expected to meet shouldof course still be satisfied. Depending on the particular application involved, these other requirements may relate, for example, to the
dielectric constant PA1 dielectric strength PA1 resistivity PA1 filler absorption by surrounding materials PA1 water (vapor) permeation. PA1 Density by weighing a defined bubble-free volume (&gt;100 ml) of the mass to be determined at the measuring temperature. The calculation is carried out in known manner. PA1 The increase in weight is determined in accordance with DIN 57472: test plates measuring 40.times.40.times.3 mm are stored in the filling compound for 10 days at 70.degree. C. The difference is gravimetrically determined. PA1 The flash point is determined in accordance with DIN ISO 2592. PA1 Fed. Test method STD. NO. 791 B or PA1 JIS K 2220, page 7 or PA1 CNET ST LAA/ELR/CSD/543,